noun

• One who or that which operates a switch.
• One who or that which switches, or changes to something else.
• (electronics) A switchmode power supply.
• (rail transport, US) A railway locomotive used for shunting; a shunter.
• (rail transport, trucking, US) The yardman who operates such an engine, or performs a similar role in a trucking depot: synonym of yard jockey.
• (television) Synonym of vision mixer (“device for selecting between video sources”)